The present invention relates to a room temperature-curable organopolysiloxane composition or, more particularly, to a room temperature-curable organopolysiloxane composition of the dealcoholation type having excellent storage stability.
Several classes of room temperature-curable organopolysiloxane compositions, referred to as the RTV compositions hereinbelow, are known in the prior art, of which the so-called dealcoholation type ones are the most important. A dealcoholation type RTV composition typically comprises an organopolysiloxane terminated at each molecular chain end with a silanolic hydroxy group, a crosslinking agent such as methyl trimethoxy silane and a curing catalyst which may be an organic titanium compound or an organic chelate compound of titanium. The curing reaction of the composition to give a rubbery cured product proceeds by the dealcoholation condensation between the silanolic hydroxy groups in the organopolysiloxane and the alkoxy groups in the crosslinking agent to produce an alcohol as the condensation by-product so that the RTV compositions of the dealcoholation type are free from the problems of corrosiveness and offensive odor as in the RTV compositions of other types. Accordingly, the RTV compositions of this type are widely used as an adhesive or other material in the electric and electronic industries.
RTV compositions of the dealcoholation type, however, are not free from some problems and disadvantages. For example, the curing velocity of the composition is usually not high enough and, in particular, complete curing of the composition can hardly be obtained in the core portion of a thick body. Further, the storage stability of the composition is relatively low so that the composition may lose curability after a long period of storage even in an anhydrous condition.
It has been proposed in view of the above mentioned problems that the RTV composition of the dealcoholation type be admixed with a special organosilane compound having two alkoxy groups in a molecule as a so-called silane scavenger to improve the curability and storage stability of the composition. This method, however, is practically not feasible since sufficient improvement of the storage stability can be obtained only when the organosilane compound has a hydrolyzable group other than alkoxy groups having high reactivity such as amido and amino groups while such reactive groups are responsible for corrosiveness and offensive odor of the composition admixed therewith so that the RTV composition can no longer be used as an adhesive in the electric and electronic industries.